1. Field of the Invention
The present invention relates generally to assays for predicting chemosensitivity, and more particularly, to a method capable of predicting the sensitivity of neoplastic cells to particular anti-cancer drugs.
Chemosensitivity of a patient tumor to particular anti-cancer drugs has heretofore been assessed in clonogenic assays, typically in agar. Cells are divided from a biopsy specimen, and single cells grown in the assay culture. Proliferating cultures are then exposed to the drug, and chemosensitivity assessed based on observed toxicity. While such assays are successful for many types of tumors, they are much less successful for certain tumors, such as breast tumors, where the cells are not easily cloned. Moreover, the effectiveness of such assays is greatly reduced if the culture medium contains components which affect the toxicity of the drug being tested.
Therefore, it would be desirable to provide alternative chemosensitivity assays which do not require cloning of the tumor cells and which do not rely on the direct observation of toxicity. It would be particularly desirable to provide such assays which are highly accurate, convenient to perform, and relatively inexpensive.
2. Description of the Relevant Art
Kaufman et al. (1978) J. Biol. Chem. 257:5852-5860, describe the use of a fluorescence activated cell sorter to quantitate levels of dihydrofolate reductase (dhfr) levels in methotrexate-resistant cell lines. Rosowsky et al. (1982) J. Biol. Chem. 257:14162-14167 describe the preparation of a particular fluorescent methotrexate analog. Johnston et al. (1983) Proc. Natl. Acad. Sci. USA 80:3711-3715, describe the use of classical fluctuation analysis to demonstrate dhfr gene amplification upon exposure to methotrexate. Cells with the highest levels of dhfr were selected by exposure to fluoresceinated methotrexate and sorting using a FACS.